I don’t see how this benefits the Dems in the November election. Whoever was going to support the Dems because of their stand on any gay oriented issue would most likely vote the Dems anyway, regardless of whether or not DADT is repealed or not. They were going to get their votes regardless.
And the Dems really don't care if they can get their agenda passed. Obamacare is going to hurt them at the polls, but they got what they wanted passed, which they have tried for decades. Repealing all of this is going to be difficult and lengthy. And many Reps don't have the stomach to do it.